I've done a lot of reading and searching over the last week or so about the AMP6 and related stuff, and am still left with a few questions. I know a bit about electronics but really just the basics (what resistors do, capacitors, relays, transistors, diodes.. maybe a few other things) and have soldered things before with decent results (although I always had a really cheap soldering iron with a huge tip -- I plan on getting a decent Weller before I attempt the AMP6). I made some LED bike lights with a 555 blink circuit, for example.
One thing I don't understand is what to do about the power supply, and how much difference it really makes. It seems that the high quality way to go is use a toroidal transformer with the non-basic AMP6. But a lot of people seem to be using wall warts or laptop power supplies with the AMP6-basic. I'm left wondering what I should do and how much it matters either way. If I do go with the non-basic and get my own transformer, is it very important to use a toroidal one? And what is meant by "15V+15V"? There's two outputs?... I don't get it.
Another thing is shielding and what kind of wires to use for the internal connections. A lot of people seem to just use plain wire, but I've also seen shielded coax used, for example. I'm not going for high end or expensive, but I figure if I can spend just a little more, I might as well do it nicely instead of crappily. Any suggestions here?
Also, some questions about attenuators: what's best? 10K? 50K? Something else? Either way, it will do the same thing, right? Go from mute to full blast? Just with more or less granularity at the lower volumes?
Ok, I think that's it for now. I'm sure I'll have more questions eventually.
One thing I don't understand is what to do about the power supply, and how much difference it really makes. It seems that the high quality way to go is use a toroidal transformer with the non-basic AMP6. But a lot of people seem to be using wall warts or laptop power supplies with the AMP6-basic. I'm left wondering what I should do and how much it matters either way. If I do go with the non-basic and get my own transformer, is it very important to use a toroidal one? And what is meant by "15V+15V"? There's two outputs?... I don't get it.
Another thing is shielding and what kind of wires to use for the internal connections. A lot of people seem to just use plain wire, but I've also seen shielded coax used, for example. I'm not going for high end or expensive, but I figure if I can spend just a little more, I might as well do it nicely instead of crappily. Any suggestions here?
Also, some questions about attenuators: what's best? 10K? 50K? Something else? Either way, it will do the same thing, right? Go from mute to full blast? Just with more or less granularity at the lower volumes?
Ok, I think that's it for now. I'm sure I'll have more questions eventually.
Garak,
Soldering the Amp 6 is really pretty easy--very little surface-mount stuff and tthose are pretty large items. So, no sweat.
If you're only going to use yours plugged-in, the built in power supply should work well. But the switching power supplies (typically for computer monitors) also work well, and will be a good deal cheaper than the transformer. Toroids deliver more power for their size and less emitted magnetic radiation than conventional types, but I doubt you could hear any audible difference. It's a single supply unit, which means there is just a positive and negative connection, two wires. Anything right up to I think about 14.5v is OK, but they run just fine on 12v.
Using shielded wires for signal runs is good practice, especially as the runs get longer. You can sacrifice an RCA cable for the purpose rather than buy new wire.
I've got a 50K pot on mine, works just fine. I don't think granularity is an issue. Do pay attention to the gain-setting choices. High-gain configuration is suitable for portable devices like iPod that have fairly low signal to conserve battery power, but if you're running off of a regular CD player, you may be happier with a lower gain setting.
--Buckapound
Soldering the Amp 6 is really pretty easy--very little surface-mount stuff and tthose are pretty large items. So, no sweat.
If you're only going to use yours plugged-in, the built in power supply should work well. But the switching power supplies (typically for computer monitors) also work well, and will be a good deal cheaper than the transformer. Toroids deliver more power for their size and less emitted magnetic radiation than conventional types, but I doubt you could hear any audible difference. It's a single supply unit, which means there is just a positive and negative connection, two wires. Anything right up to I think about 14.5v is OK, but they run just fine on 12v.
Using shielded wires for signal runs is good practice, especially as the runs get longer. You can sacrifice an RCA cable for the purpose rather than buy new wire.
I've got a 50K pot on mine, works just fine. I don't think granularity is an issue. Do pay attention to the gain-setting choices. High-gain configuration is suitable for portable devices like iPod that have fairly low signal to conserve battery power, but if you're running off of a regular CD player, you may be happier with a lower gain setting.
--Buckapound
I agree with Buckapound.
Furthermore, I've built an Amp6 with a nice, heavy toroid, and also an Amp6-BASIC with a cheap SMPS. I couldn't tell any difference at all. I haven't done extensive double-blind testing, but there's certainly nothing amiss with the SMPS powered amp.
I think the gain of 2.5 on the BASIC I built is a little high. I would go for a gain of 2 if I were to do it again, but it's not so important that I will be changing the amp.
Furthermore, I've built an Amp6 with a nice, heavy toroid, and also an Amp6-BASIC with a cheap SMPS. I couldn't tell any difference at all. I haven't done extensive double-blind testing, but there's certainly nothing amiss with the SMPS powered amp.
I think the gain of 2.5 on the BASIC I built is a little high. I would go for a gain of 2 if I were to do it again, but it's not so important that I will be changing the amp.
Here's a little diagram i made. Pretty straight forward but I just wanted to get everything out of my head and "on paper." Feel free to pick out any flaws. One thing I got confused about was whether the input grounds should be separated (and thus need their own poles on the input switches). I'm still not quite sure but I'm leaning towards yes.
Attachments
Thanks for the advice. I will usually be using it plugged into my computer, listening to music, and once in a while with game consoles. The game consoles always seem to be much louder than my computer.
Sounds like I'll just end up going with the basic after all. I hate external power bricks though, so maybe I'll embed the brick inside the chassis of this thing.
You think a beer can would be good enough for a heat sink? I could slide the board inside a can with its ends cut off (or maybe one end left on), and screw the three hot thingies to it. Just an idea. I'll rarely turn it up very loud, and what would happen if it gets too hot anyway? Just distort more? I can live with that...
Sounds like I'll just end up going with the basic after all. I hate external power bricks though, so maybe I'll embed the brick inside the chassis of this thing.
You think a beer can would be good enough for a heat sink? I could slide the board inside a can with its ends cut off (or maybe one end left on), and screw the three hot thingies to it. Just an idea. I'll rarely turn it up very loud, and what would happen if it gets too hot anyway? Just distort more? I can live with that...
garak said:
Hi, I want to say a bit more about this -
It will do the exact same thing with respect to its purpose of controlling volume.
However, there are two potential side effects between different pots: Interplay with input impedance and, in the case of the Amp6, there's a slight variation of the voltage gain of the amplifier. If I understand all of this correctly. I assume that the instructions recommend a 50K pot because of these side effects. (By the way - this is not stuff you need to worry about as a fresh DIYer.)
I really want to make this thing fully integrated and basically have the features I like from a mainstream stereo receiver -- headphones being one thing. Unfortunately that's a whole other can of worms... but since I only use it occasionally, and headphones seem to sound great even with mediocre-quality equipment, I thought I would go the cheap, pre-made route. I'm going to get a little Behringer mini headphone amp and stick it inside my reciever. The only thing I wonder about is, will the switching power supply cause it to be noisy? I assume it comes with a wall wart, and I would rather not also have THAT inside my receiver, especially because it draws a tiny bit of energy 24/7 and I'd have to have some sort of AC switch to cut it off when not in use... which is way too complicated. I figure I'll just switch the 12V connection between the headphone amp (it runs on 12V) and the AMP6. Does this make sense?
Shopping for electronic parts is possibly the worst thing ever. Parts Express has a friendly site with pictures of everything, but they only stock basic stuff. The big distributors like Mouser and DigiKey have everything, but it's a nightmare to search for it, and there's hardly any pictures.
This is probably a stretch, but is there any place I can get decent cheap (<$10) gold binding posts (like the ones at Parts Express), gold RCA jacks, an IEC socket, AND 4PDT on-off-on switches? Parts Express is missing the latter, and the only way I can seem to find them is at places that either don't offer the other parts, or make it a nightmare to find them. It seems stupid to pay shipping twice for such tiny parts. I checked out my local distributors, but as you might expect, their websites are completely horrible. How do you guys put up with this?
This is probably a stretch, but is there any place I can get decent cheap (<$10) gold binding posts (like the ones at Parts Express), gold RCA jacks, an IEC socket, AND 4PDT on-off-on switches? Parts Express is missing the latter, and the only way I can seem to find them is at places that either don't offer the other parts, or make it a nightmare to find them. It seems stupid to pay shipping twice for such tiny parts. I checked out my local distributors, but as you might expect, their websites are completely horrible. How do you guys put up with this?
parts geekiness
You have to wait,but what about cheap chinese amps.they often use lots of shiney stuff.
regards
max
http://cgi.ebay.co.uk/Hi-Fi-Audio-S...temQQimsxZ20081020?IMSfp=TL081020127003r10192
ps there,s always the dump....recycling centre.
You have to wait,but what about cheap chinese amps.they often use lots of shiney stuff.
regards
max
http://cgi.ebay.co.uk/Hi-Fi-Audio-S...temQQimsxZ20081020?IMSfp=TL081020127003r10192
ps there,s always the dump....recycling centre.
Re: parts geekiness
Yes, I second this ... grampa always says he's going to the "pawn shop" when he's scrounging for electronics at the dump
also, people also tend to hang on to big, clunky, broken amplifiers that were expensive in the '70s. They just can't bear to throw them away. There's lots of goodies in those, especially the mechanical bits. Call your friends.
albin said:
Yes, I second this ... grampa always says he's going to the "pawn shop" when he's scrounging for electronics at the dump
also, people also tend to hang on to big, clunky, broken amplifiers that were expensive in the '70s. They just can't bear to throw them away. There's lots of goodies in those, especially the mechanical bits. Call your friends.
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